Structural stability of SiGe nanoparticles under "in situ" electron beam irradiation in TEM

The structure of amorphous and crystalline SiGe nanoparticles, embedded in a dielectric medium, SiO2, and its stability under “in situ” electron beam irradiation is reported. High-resolution transmission electron microscopy and electron-diffraction pattern simulation by fast Fourier transform was used to analyze the crystal structure of the SiGe nanoparticles. Electron beam irradiation induces structural alternate order-disorder transitions in the nanoparticles for irradiation effects are mainly associated to the density of current. For irradiation with current densities < 7 A·cm-2 no effects are observed in the as-deposited amorphous samples, whereas in the crystallized samples, SiGe nanocrystals show higher stability and no effects are observed for irradiation densities of current < 50 A·cm-2. Irradiation with densities of current greater than these thresholds cause consecutive amorphous-crystalline or crystalline-amorphous structure transitions respectively for both amorphous and crystallized nanoparticles. A hexagonal structure is proposed for those nanocrystals obtained after irradiation in the as deposited amorphous samples

El papel de las universidades en el fomento de la emprendeduría turística: el caso de la Universidad de La Laguna

En el presente trabajo se trata de explorar la importancia de la formación y promoción de la emprendeduría en el ámbito universitario para los futuros profesionales del sector turístico, teniendo en cuenta el contexto de creciente competitividad a que van a enfrentarse en su vida profesional. Más específicamente se presentará la metodología y principales resultados de una experiencia concreta, la que se viene desarrollando en la Universidad de La Laguna (Islas Canarias, España) bajo la marca Emprende.ull.In the present work we try to explore the importance of entrepreneurship formation and promotion at university level for tourism students, considering the context of increasing competitiveness to that they are going to face in its professional life. More specifically, we present the methodology and main results of a concrete experience which has come developing in the University of La Laguna (Canary Islands, Spain): Emprende.ull

Análisis de la tasa de abandono de primer año del Grado en Estadística Aplicada. Evolución y proyección

Fac. de Estudios EstadísticosFALSEsubmitte

Oral Chronic Toxicity of the Safe Tetrodotoxin Dose Proposed by the European Food Safety Authority and Its Additive Effect with Saxitoxin

Tetrodotoxin (TTX) is a potent natural toxin causative of human food intoxications that shares its mechanism of action with the paralytic shellfish toxin saxitoxin (STX). Both toxins act as potent blockers of voltage-gated sodium channels. Although human intoxications by TTX were initially described in Japan, nowadays increasing concern about the regulation of this toxin in Europe has emerged due to its detection in fish and mollusks captured in European waters. Currently, TTX is only regularly monitored in Dutch fishery products. However, the European Food Safety Authority (EFSA) has established a safety level of 44 µg/kg TTX as the amount of toxin that did not cause adverse effects in humans. This level was extrapolated considering initial data on its acute oral toxicity and EFSA remarked the need for chronic toxicity studies to further reduce the uncertainty of future toxin regulations. Thus, in this work, we evaluated the oral chronic toxicity of TTX using the safety levels initially recommended by EFSA in order to exclude potential human health risks associated with the worldwide expanding presence of TTX. Using internationally recommended guidelines for the assessment of oral chronic toxicity, the data provided here support the proposed safety level for TTX as low enough to prevent human adverse effects of TTX even after chronic daily exposure to the toxin. However, the combination of TTX with STX at doses above the maximal exposure level of 5.3 µg/kg body weight derived by EFSA increased the lethality of TTX, thus confirming that both TTX and paralytic shellfish toxins should be taken into account to assess human health risksThe research leading to these results has received funding from the following European Regional Development Fund (FEDER) cofunded grants. From Conselleria de Cultura, Educacion e Ordenación Universitaria, Xunta de Galicia, 2017 GRC GI-1682 (ED431C 2017/01). From the Centre for the Development of Industrial Technology (CDTI) and Technological Funds, supported by Ministerio de Economía, Industria y Competitividad, (AEI/FEDER, UE), ISCIII/PI16/01830 and RTC-2016-5507-2, ITC-20161072S

Ptpn1 deletion protects oval vells against lipoapotosis by favoring lipid droplet formation and dynamics

Trabajo presentado en el The international liver congress, celebrado en Londres (Inglaterra) del 22 al 26 de junio de 2022.[Background and aims]: Activation of oval cells has been related to hepatocyte injury during chronic liver diseases including nonalcoholic fatty liver disease (NAFLD). However, oval cells plasticity can be affected by the pathological environment. We previously found a protection against hepatocyte cell death by inhibiting protein tyrosine phosphatase 1B (PTP1B). Herein, we investigated the molecular and cellular processes involved in the lipotoxic susceptibility in oval cells expressing or not PTP1B. [Method]: Palmitic acid (PA) induced apoptotic cell death in wild-type (Ptpn1+/+) oval cells in parallel to oxidative stress and impaired autophagy. This lipotoxic effect was attenuated in oval cells lacking Ptpn1 that showed up-regulated antioxidant defences, increased unfolded protein response (UPR) signaling, higher endoplasmic reticulum (ER) content and elevated stearoyl CoA desaturase (Scd1) expression and activity. [Results]: These effects in Ptpn1−/− oval cells concurred with an active autophagy, higher mitochondrial efficiency and a molecular signature of starvation, favoring lipid droplet (LD) formation and dynamics. Autophagy blockade in Ptpn1−/− oval cells reduced Scd1 expression, mitochondrial fitness, LD formation and restored lipoapoptosis, an effect also recapitulated by Scd1 silencing. Importantly, oval cells with LDs were found in livers from Ptpn1−/− mice with NAFLD. [Conclusion]: Ptpn1 deficiency restrained lipoapoptosis in oval cells through a metabolic rewiring towards a “starvation-like” fate, favoring autophagy, mitochondrial fitness and LD formation. Dynamic LD-lysosomal interations likely ensured lipid recycling and, overall, these adaptations protect against lipotoxicity. The identification of LDs in oval cells from Ptpn1−/− mice with NAFLD opens new therapeutic perspectives to ensure oval cells viability and plasticity under lipotoxic liver damage

Free amino acids, urea and ammonium ion contents for submerged wine vinegar production: influence of loading rate and air-flow rate

The nitrogen source for acetic acid bacteria is important during the vinegar making process. There can be great variation in the final result according to the specific source, the total nitrogen availability and the operational conditions. These bacteria use L-proline, L-leucine and ammonium ion as their main source of nitrogen from white wine. The effect of loading and air-flow rates on the changes in amino acids, urea and ammonium ion contents have been studied for a semi-batch submerged wine vinegar controlled production. Experiments were carried out in a Frings 8L fermenter working in a semi-batch mode. Amino acid contents were determined from their dansyl derivatives on an HPLC furnished with a C18 reversed-phase column. Urea and ammonium ion contents were quantified with an enzymatic kit. Specific nitrogen consumption is given for 25 amino acids and ammonium ion. In addition, profiles for main system variables as well as the three main nitrogen sources (ammonium ion, L-leucine and L-proline) are given. Type of loading and air-flow rates seemed to have a strong impact on the consumption of the nitrogen compounds tested. An increased loading rate and decreased air-flow rate resulted in greater overall consumption of available nitrogen due to different causes. Nitrogen requirement of the bacteria is proportional to the time spent in the acetification process. An acetification procedure involving relatively sudden changes in the fermentation medium may be desirable in order to reduce the formation of urea

The photosynthetic cytochrome c550 from the diatom Phaeodactylum tricornutum

The photosynthetic cytochrome c550 from the marine diatom Phaeodactylum tricornutum has been purified and characterized. Cytochrome c550 is mostly obtained from the soluble cell extract in relatively large amounts. In addition, the protein appeared to be truncated in the last hydrophobic residues of the C-terminus, both in the soluble cytochrome c550 and in the protein extracted from the membrane fraction, as deduced by mass spectrometry analysis and the comparison with the gene sequence. Interestingly, it has been described that the C-terminus of cytochrome c550 forms a hydrophobic finger involved in the interaction with photosystem II in cyanobacteria. Cytochrome c550 was almost absent in solubilized photosystem II complex samples, in contrast with the PsbO and Psb31 extrinsic subunits, thus suggesting a lower affinity of cytochrome c550 for the photosystem II complex. Under iron-limiting conditions the amount of cytochrome c550 decreases up to about 45% as compared to iron-replete cells, pointing to an iron-regulated synthesis. Oxidized cytochrome c550 has been characterized using continuous wave EPR and pulse techniques, including HYSCORE, and the obtained results have been interpreted in terms of the electrostatic charge distribution in the surroundings of the heme centre.España, MINECO BIO2012-35271, BIO2015-64169-P, MAT2011-23861 and CTQ2015-64486-

Deep Phenotypic Characterisation of CTCs by Combination of Microfluidic Isolation (IsoFlux) and Imaging Flow Cytometry (ImageStream)

Ines Aznar-Peralta holds a "Garantia Juvenil" fellowship (contract number 8040), and M. Carmen Garrido-Navas has a postdoctoral fellowship funded by the Ministry of Economy, Competitiveness, Enterprises and Universities (DOC_01682).The isolation of circulating tumour cells (CTCs) in colorectal cancer (CRC) mostly relies on the expression of epithelial markers such as EpCAM, and phenotypic characterisation is usually performed under fluorescence microscopy with only one or two additional markers. This limits the ability to detect different CTC subpopulations based on multiple markers. The aim of this work was to develop a novel protocol combining two platforms (IsoFluxTM and ImageStream®X) to improve CTC evaluation. Cancer cell lines and peripheral blood from healthy donors were used to evaluate the efficiency of each platform independently and in combination. Peripheral blood was extracted from 16 early CRC patients (before loco-regional surgery) to demonstrate the suitability of the protocol for CTC assessment. Additionally, peripheral blood was extracted from nine patients one month after surgery to validate the utility of our protocol for identifying CTC subpopulation changes over time. Results: Our protocol had a mean recovery efficiency of 69.5% and a limit of detection of at least four cells per millilitre. We developed an analysis method to reduce noise from magnetic beads used for CTC isolation. CTCs were isolated from CRC patients with a median of 37 CTCs (IQ 13.0–85.5) at baseline. CTCs from CRC patients were significantly (p < 0.0001) larger than cytokeratin (CK)-negative cells, and patients were stratified into two groups based on BRAFV600E and PD-L1 expression on CK-positive cells. The changes observed over time included not only the number of CTCs but also their distribution into four different subpopulations defined according to BRAFV600E and PD-L1 positivity. We developed a novel protocol for semi-automatic CTC isolation and phenotypic characterisation by combining two platforms. Assessment of CTCs from early CRC patients using our protocol allowed the identification of two clusters of patients with changing phenotypes over time."Garantia Juvenil" fellowship 8040Ministry of Economy, Competitiveness, Enterprises and Universities DOC_0168

Condicionantes de la intención emprendedora en el alumnado universitario: un análisis desde la perspectiva de género

ABSTRACT The present study focus on the effectiveness of entrepreneurship education as an instrument for the promotion of the entrepreneurial intention, as well as the influence of gender in the implementation of new business initiatives. Adopting the perspective of the theory of planned behavior, the differential effect of gender on entrepreneurship intention in a group of participants in an entrepreneurship education project in the university context is analyzed. The results suggest that, although there were no gender differences in the levels of entrepreneurial intention, the predictor variables of this dimension differ depending on the sex of participants. Thus, in the case of men, self-efficacy is the main explanatory variable of entrepreneurial intention, whereas for women the most predictor variable is perceived controllability. These results may have important implications for the design of enterprise education programs in relation to the need for pedagogical elements that distinguish the skills and competencies to be developed for women and men, in order to achieve improvements in their entrepreneurial intention.En el presente trabajo se parte de las evidencias, constatadas en la literatura, en relación con la eficacia de la educación emprendedora como instrumento para el fomento de la intención de emprender, así como de la influencia de la variable género en la puesta en marcha de nuevas iniciativas empresariales. Adoptando la perspectiva de la teoría de la acción planificada, se analiza el efecto diferencial del género sobre la intención de emprender entre un grupo de alumnos/as participantes en un proyecto de educación emprendedora en el contexto universitario. Los resultados apuntan a que, si bien no se han encontrado diferencias de género en los niveles de intención emprendedora, sí que las variables predictoras de la misma difieren en función del sexo de los participantes. Así, en el caso de los hombres, la autoeficacia es la principal variable explicativa de la intención emprendedora, mientras que para las mujeres el factor determinante es la controlabilidad percibida. Este hecho puede tener importantes implicaciones de cara al diseño de programas de educación emprendedora, en relación con la necesidad de introducir elementos pedagógicos que distingan las capacidades y competencias a desarrollar para mujeres y hombres de cara a lograr mejoras de su intención emprendedora.&nbsp; ABSTRACT The present study focus on the effectiveness of entrepreneurship education as an instrument for the promotion of the entrepreneurial intention, as well as the influence of gender in the implementation of new business initiatives. Adopting the perspective of the theory of planned behavior, the differential effect of gender on entrepreneurship intention in a group of participants in an entrepreneurship education project in the university context is analyzed. The results suggest that, although there were no gender differences in the levels of entrepreneurial intention, the predictor variables of this dimension differ depending on the sex of participants. Thus, in the case of men, self-efficacy is the main explanatory variable of entrepreneurial intention, whereas for women the most predictor variable is perceived controllability. These results may have important implications for the design of enterprise education programs in relation to the need for pedagogical elements that distinguish the skills and competencies to be developed for women and men, in order to achieve improvements in their entrepreneurial intention

Uso la plataforma H5P de creación de contenido interactivo como herramienta para la creación de un laboratorio de bioquímica virtual e interactivo

En este proyecto de innovación docente está diseñado para que el alumnado se acerque a un laboratorio de bioquímica virtual e interactivo y conozca los diferentes métodos y técnicas experimentales que se utilizan en ciertos análisis clínicos